Elevator installations with several elevator cars in the same shaft, which are also termed multi-mobile elevator installations, usually have a respective driving and braking system per elevator car. Moreover, such elevator installations are equipped with a collision protection system by which collisions of the elevator cars are to be avoided.
Apart from conventional electronically controlled collision protection systems an elevator installation with a collision protection system with electromechanical switching mechanisms able to be mechanically triggered has been described by European Patent Application EP 06 120 359. The disclosure of this European Patent Application is regarded as an integral part of the present application. The mentioned collision protection system is simple in construction and reliable in its operation. However, it is disadvantageous that its triggering takes place merely when a critical minimum distance between two approaching elevator cars is fallen below without further braking criteria such as, for example, the relative speed between the elevator cars or the instantaneous effective distance, in each instance after triggering of the stopping brake, being taken into consideration. Particularly in the case of high car speeds and emergency situations it cannot be guaranteed with ultimate certainty that a further elevator car disposed above or below still stops at the right time to avoid a collision.